Validation of a subclassification for high-risk prostate cancer in a prospective cohort

Abstract

Background: A subgroup of men with favorable high-risk prostate cancer (T1c with either a Gleason score of 4 + 4 = 8 and a prostate-specific antigen [PSA] level <10 ng/mL or a Gleason score of 6 and a PSA level >20 ng/mL) has been associated with improved outcomes in comparison with other standard high-risk patients. This study was designed to validate the prognostic utility of a subclassification for high-risk disease with a prospectively collected data set. Methods: This study identified 3033 men from the Prostate, Lung, Colorectal, and Ovarian Cancer Screening Trial who had been diagnosed from 1993 to 2001 with clinically localized prostate cancer—either intermediate-risk disease (clinical stage T2b-c, a Gleason score of 7, or a PSA level of 10 to 20 ng/mL) or high-risk disease (clinical stage T3-T4, a Gleason score of 8-10, or a PSA level >20 ng/mL)—that was managed with radical prostatectomy or radiation therapy. Multivariable logistic regression was used to calculate adjusted odds ratios (aORs) for pathological T3 to T4 or N1 (pT3-T4/pN1) disease. Fine and Gray competing risks regression was used to determine adjusted hazard ratios (aHRs) of prostate cancer–specific mortality (PCSM). Results: The median follow-up was 5.7 years. Patients with favorable high-risk disease had lower 8-year PCSM in comparison with patients with standard high-risk disease (2.2% vs 10.8%; aHR, 0.26; 95% confidence interval [CI], 0.09-0.73; P =.01) but similar PCSM in comparison with patients with intermediate-risk disease (2.2% vs 2.2%; aHR, 0.90; 95% CI, 0.32-2.54; P =.84). Among those who underwent surgery, those with favorable high-risk disease had lower odds of pT3-T4/pN1 disease than those with standard high-risk disease (46.2% vs 63.3%; aOR, 0.50; 95% CI, 0.27-0.94; P =.03). Conclusions: This study validates the prognostic utility of a subclassification for high-risk disease in a prospectively collected patient cohort. Patients with favorable high-risk disease have PCSM similar to that of patients with intermediate-risk disease and significantly better than that of patients with standard high-risk disease. Future trials are needed to assess possible de-intensification of therapy for favorable high-risk disease.